Lack of association of the TP53 Arg72Pro SNP and the MDM2 SNP309 with systemic lupus erythematosus in Caucasian, African American, and Asian children and adults

TP53 and p21 (CDKN1A) polymorphisms and the risk of systemic lupus erythematosus

BACKGROUND

The p53 and p21 proteins are important regulators of cell cycle and apoptosis and may contribute to autoimmune diseases, such as systemic lupus erythematosus (SLE). As genetic polymorphisms may cause changes in protein levels and functions, we investigated associations of TP53 and p21 (CDKN1A) polymorphisms (p53 72 G > C-rs1042522; p53 PIN3-rs17878362; p21 31 C > A-rs1801270; p21 70 C > T-rs1059234) with the development of systemic lupus erythematosus (SLE) in a Southeastern Brazilian population.

METHODS

Genotyping of 353 female volunteers (cases, n = 145; controls, n = 208) was performed by polymerase chain reaction, restriction fragment length polymorphism and/or DNA sequencing. Associations between TP53 and p21 polymorphisms and SLE susceptibility and clinical manifestations of SLE patients were assessed by logistic regression analysis.

RESULTS

Protective effect was observed for the genotype combinations p53 PIN3 A1/A1-p21 31 C/A, in the total study population (OR 0.45), and p53 PIN3 A1/A2-p21 31 C/C, in non-white women (OR 0.28). In Whites, p53 72 C-containing (OR 3.06) and p53 PIN3 A2-containing (OR 6.93) genotypes were associated with SLE risk, and higher OR value was observed for the combined genotype p53 72 G/C-p53 PIN3 A1/A2 (OR 9.00). Further, p53 PIN3 A1/A2 genotype was associated with serositis (OR 2.82), while p53 PIN3 A2/A2 and p53 72 C/C genotypes were associated with neurological disorders (OR 4.69 and OR 3.34, respectively).

CONCLUSIONS

Our findings showed that the TP53 and p21 polymorphisms included in this study may have potential to emerge as SLE susceptibility markers for specific groups of patients. Significant interactions of the TP53 polymorphisms with serositis and neurological disorders were also observed in SLE patients.

Integrative analysis of omics summary data reveals putative mechanisms linked to different cell populations in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex disease involving many interactions at the molecular level, the details of which remain unclear. Here, we demonstrated an analytical paradigm of prioritizing genes and regulatory elements based on GWAS loci at the single-cell levels. Our initial step was to apply TWMR to identify causal genes and causal methylation sites in SLE. Based on the eQTL, LD and mQTL, we calculated the correlation between these genes and methylation sites. Next, we separately used gene expression and DNAm as exposure variables and outcome variables to analyze the regulatory mechanisms. We identified two mediating modes for SLE: 1) transcription mediation model and 2) epigenetic mediation model. Further, using single-cell RNA sequencing data, we revealed the cell subclusters associated with these mechanisms. Our identification of the mechanisms of SLE in different cell populations is of great significance for understanding the heterogeneity of disease in different cell populations.

Investigating the Molecular Mechanism of Xijiao Dihuang Decoction for the Treatment of SLE Based on Network Pharmacology and Molecular Docking Analysis

Objective

To elucidate the main mechanism of Xijiao Dihuang decoction (XJDHT) for the treatment of systemic lupus erythematosus (SLE).

Methods

TCMSP, BATMAN-TCM, ETCM, and TCMID databases and literature search were used to screen the potential active compounds of XJDHT, and TCMSP and SwissProt databases were searched to predict the targets of the compounds. The targets of SLE were obtained from Genegards, OMIM, and DisGeNET databases, and Venn online platform was used to obtain the intersection targets of XJDHT and SLE. Afterwards, the PPI network was constructed by using the STRING database, and the core targets were identified by network topology analysis. GO and KEGG enrichment analyses were performed through R software, and molecular docking of the top three core targets and their corresponding compounds were accomplished by Autodock Vina and Pymol softwares.

Results

There were 30 potential active ingredients, 289 potential targets, and 129 intersection targets screened from the above databases. Network topology analysis identified 23 core targets, such as AKT1, TNF, IL6, IL1B, and INS. GO enrichment analysis obtained 2555 terms and mainly clustering on the react to lipopolysaccharide, membrane raft, and ubiquitin-like protein ligase binding. KEGG enrichment analysis obtained 187 signaling pathways, mainly concentrating on the lipid and atherosclerosis, AGE-RAGE signaling pathway in diabetic complications, fluid shear stress, and atherosclerosis. Molecular docking verified that the active compounds of XJDHT have the strong binding activity to the core targets.

Conclusion

This study preliminarily uncovers the mechanism of XJDHT acting on SLE through a “multicompound, multitarget, and multipathway” manner. XJDHT may achieve the treatment of SLE by inhibiting the proinflammatory factors, inflammatory signal cvtokines, proliferation, injury, and apoptosis processes. In summary, the present study would provide a promising theoretical basis for further clinical and experimental studies.

Bioinformatics Analysis of the Core Genes Related to Lupus Nephritis Through a Network and Pathway-Based Approach

In this study, we explored the genes genetically associated with lupus nephritis (LN), and their function by bioinformatics analysis. We collected genes potentially associated with LN from National Center for Biotechnology Information Center (NCBI-Gene) and Online Mendelian Inheritance in Man (OMIM) databases. The major bioinformatics analysis linked with genes was then revealed by weighted gene co-expression network analysis (WGCNA), crosstalk analysis, functional analysis, and Pivot algorithm. Two hundred twenty-three LN-related genes were obtained by intersecting NCBI-Gene and OMIM databases. Two thousand five hundred sixty-eight LN-related proteins and 23 modules were excavated by String protein interaction network and WGCNA co-expression analysis, respectively. Pivot algorithm included no coding RNA, transcription factor and drug indicated the high-count correlation-associated modules related to cancer, kidney pathophysiological changes, and kidney injury, respectively. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis based on 23 modules revealed LN-related genes mainly involved in immune response. Moreover, 19 genes that came from intersection of LN, arthritis, pleurisy, and myocarditis have close relationship with immune diseases and immune processes. Our results from this research may have important implications for understanding the genes underlying LN. Also, the framework proposed in this work can be used to research pathological molecular network and genes related to LN.

Mechanistic insights into environmental and genetic risk factors for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organ systems with diverse presentation, primarily affecting women of reproductive age. Various genetic and environmental risk factors are involved in the pathogenesis of SLE, and many SLE susceptibility genes have been identified recently; however, gene therapy is not a viable clinical option at this time. Thus, environmental risks factors, particularly regional characteristics that can be controlled, need to be further investigated. Here, we systematically explored these risk factors, including ultraviolet radiation, seasonal distribution, geographical distribution, and climate factors, and also summarized the mechanisms related to these risk factors. Probable mechanisms were explicated in at least four aspects including inflammatory mediators, apoptosis and autophagy in keratinocytes, epigenetic factors, and gene-environment interactions. This information is expected to provide practical insights into these risk factors in order to benefit patients with SLE and facilitate the development of potential therapeutic strategies.

Pubertal and adult windows of susceptibility to a high animal fat diet in Trp53-null mammary tumorigenesis

Premenopausal breast cancer is associated with increased animal fat consumption among normal weight, but not overweight women (Farvid et al., 2014). Our previous findings in obesity-resistant BALB/c mice similarly showed promotion of carcinogen-induced mammary tumorigenesis by a diet high in saturated animal fat (HFD). This effect was specific to pubertal versus adult HFD. This study identifies the effects of HFD during puberty versus adulthood in Trp53-null transplant BALB/c mice and investigates its mechanism of enhancing tumorigenesis. Either pubertal or adult HFD is sufficient to increase incidence of Trp53-null mammary tumors. Puberty-restricted HFD exposure promoted tumor cell proliferation, increased angiogenesis, and increased recruitment of total and M2 macrophages in epithelial tumors. Adult-restricted exposure to HFD similarly increased proliferation, angiogenesis, recruitment of total and M2 macrophages, and additionally reduced apoptosis. Adult HFD also increased incidence of spindle cell carcinomas resembling claudin-low breast cancer, and thus adult HFD in the Trp53-null transplantation system may be a useful model for human claudin low breast cancer. Importantly, these results on Trp53-null and our prior studies on DMBA-induced mammary tumorigenesis demonstrate a pubertal window of susceptibility to the promotional effects of HFD, indicating the potential of early life dietary intervention to reduce breast cancer risk.

Expression and Polymorphisms of Lysosome-Associated Protein Transmembrane 5 (LAPTM5) in Patients with Systemic Lupus Erythematosus in a Chinese Population

Lysosome-associated protein transmembrane 5 (LAPTM5) have been demonstrated a role in the prevention of lymphocyte hyperactivation, and its deficiency is involved in the immunological dysfunction of mouse models. The aim of this study was to detect mRNA expression of LAPTM5 in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE), and to assess association between LAPTM5 single nucleotide polymorphisms (SNPs) (rs10798801, rs4614309, rs1188348, and rs1188349) and SLE in a Chinese population. Real-time transcription-polymerase chain reaction analysis was used to determine expression of LAPTM5 mRNA in PBMCs from 132 patients with SLE and 62 healthy controls. LAPTM5 mRNA expression decreased in SLE patients (n = 71) compared with healthy controls (n = 58) (p = 3.68 × 10(-5)). The expression of LAPTM5 mRNA in SLE patients with lupus nephritis (LN) (n = 35) was lower than in those without LN (n = 36) (p = 0.004). The expression level of LAPTM5 correlated with serum total protein (r(s) = 0.41, p = 0.027) and negatively correlated with 24-h proteinuria (r(s) = -0.45, p = 0.027). LAPTM5 SNPs (rs10798801, rs4614309, rs1188348, and rs1188349) was also analyzed by restriction fragment length polymorphism (RFLP) in 380 SLE patients and 460 healthy controls. No significant difference in the genotype or allele frequencies for LAPTM5 SNPs was detected in 380 SLE patients and 460 healthy controls (p > 0.05). Substantially low frequency of GGAT haplotype was observed in SLE patients (p < 0.001). It is concluded that insufficient expression of LAPTM5 may take part in the pathogenesis of SLE and contribute to the severity of the disease, and none of LAPTM5 polymorphisms contributes significantly to SLE susceptibility in a Chinese population.

Polymorphisms in DNA repair genes and breast cancer risk in Russian population: a case-control study

Genetic variation in DNA repair genes can alter an individual's capacity to repair damaged DNA and influence the risk of cancer. We tested seven polymorphisms in DNA repair genes XRCC1, ERCC2, XRCC3, XRCC2, EXOI and TP53 for a possible association with breast cancer risk in a sample of 672 case and 672 control Russian women. An association was observed for allele A of the polymorphism XRCC1 (R399Q) rs25487 (co-dominant model AA vs. GG: OR 1.76, P = 0.003; additive model OR 1.28, P = 0.005; dominant model: OR 1.29, P = 0.03; recessive model OR 1.63, P = 0.008). Allele T of the polymorphism ERCC2 (D312N) rs1799793 was also associated with breast cancer risk (co-dominant model TT vs. CC: OR 1.43, P = 0.04; additive model OR 1.21, P = 0.02; dominant model: OR 1.30, P = 0.02), but the association became insignificant after applying Bonferroni correction. No association with breast cancer was found for the remaining SNPs. In summary, our study provides evidence that polymorphisms in DNA repair genes may play a role in susceptibility to breast cancer in the population of ethnical Russians.

Associations between the p53 codon 72 polymorphisms and susceptibility to systemic lupus erythematosus and rheumatoid arthritis: a meta-analysis

Objective: The aim of this study was to determine whether the p53 codon 72 polymorphism confers susceptibility to systemic lupus erythematous (SLE) and rheumatoid arthritis (RA). Methods: A meta-analysis was conducted on the associations between the p53 codon 72 polymorphism and SLE or RA using: 1) allele contrast; 2) the recessive model; 3) the dominant model; and 4) the additive model. Results: A total of 10 studies, that is, 6 SLE and 4 RA studies, involving 1578 patients and 3138 controls were considered in the meta-analysis. Meta-analysis of the p53 codon 72 polymorphism showed no association between patients and the C allele (odds ratio (OR) = 0.834, 95% confidence interval (CI) = 0.599-1.161, p = 0.282), or between SLE and the p53 C allele (OR = 0.998, 95% CI = 0.765-1.302, p = 0.989). However, stratification by ethnicity showed an association between the p53 C allele and SLE in Asians (OR = 1.410, 95% CI = 1.044-1.906, p = 0.025), but not in Europeans (OR = 0.871, 95% CI = 0.625-1.214, p = 0.415). Furthermore, an association was found between the polymorphism and SLE in Asians using recessive and additive models. However, no association was found between RA and the p53 codon 72 polymorphism in all study subjects or in Europeans. Conclusions: This meta-analysis demonstrates that the p53 codon 72 polymorphism may confer susceptibility to SLE in Asians, but not in Europeans.